Group of Analytical Spectroscopy and Sensors (GEAS), Institute of Environmental Sciences (IUCA), University of Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain.
Anal Bioanal Chem. 2023 May;415(11):2101-2112. doi: 10.1007/s00216-022-04215-z. Epub 2022 Jul 30.
Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is a technique widely used to obtain direct information about the number concentration and the size distribution of nanoparticles in liquid suspensions. However, its methods still lack clear quality control strategies to confirm the validity of the information derived from them. Only the detection of the complete size distribution of the nanoparticles in a sample over the size critical value ensures obtaining unbiased quantitative information, otherwise information should be restricted to report the presence of nanoparticles over a certain size and number concentration since their actual total number concentration is underestimated and the size overestimated. Under the latter conditions, data processing produces histograms showing the tails of the incomplete size distributions, although apparently, complete distributions can also be obtained when particle events are recorded as peaks, as reported here for the first time. The occurrence of these misleading situations must be critically evaluated for each SP-ICP-MS analysis. An approach, based on estimation of size critical values and successive dilutions, is proposed for the assessment of the validity of the quantitative information obtained, together with specific criteria for reconsidering the information that can be derived from those measurements. The approach was verified with different case studies and applied to the analysis of complex nanomaterials, confirming the validity of the reported information by comparison with other techniques. A calculation tool is also included to facilitate the estimation of size critical values under experimental conditions.
单颗粒电感耦合等离子体质谱 (SP-ICP-MS) 是一种广泛用于获取液体悬浮液中纳米颗粒数量浓度和粒径分布直接信息的技术。然而，其方法仍然缺乏明确的质量控制策略来确认从这些信息中得出的有效性。只有在样品中检测到超过尺寸临界值的完整纳米颗粒尺寸分布，才能获得无偏的定量信息，否则，信息应限于报告一定尺寸和数量浓度以上的纳米颗粒的存在，因为它们的实际总数浓度被低估，尺寸被高估。在后一种情况下，数据处理会生成显示不完整尺寸分布尾部的直方图，尽管显然，正如这里首次报道的那样，当以峰形式记录颗粒事件时，也可以获得完整的分布。对于每个 SP-ICP-MS 分析，都必须对这些误导情况进行严格评估。提出了一种基于尺寸临界值估计和连续稀释的方法来评估所获得定量信息的有效性，并提出了用于重新考虑可从这些测量中得出的信息的具体标准。该方法已通过不同的案例研究进行了验证，并应用于复杂纳米材料的分析，通过与其他技术进行比较，证实了所报告信息的有效性。还包括一个计算工具，以方便在实验条件下估计尺寸临界值。
